Rectangular steel tubes with timber infill and CFRP confinement under compression: experiments

A new composite element comprising rectangular steel tubular sections filled with timber and confined with carbon fiber reinforced polymer (CFRP) was investigated in this study. Several tests were conducted on different specimens with varying geometrical conditions and the impact of each material was studied on the structural behavior of these members under axial compression. The timber infill was found to significantly improve the capacity by preventing local inward buckling. This effect was further enhanced when the short columns were confined with sufficient layers of CFRP to prevent local outward buckling. In both cases the strength increase (up to 75%) was substantially greater than the corresponding weight increase (up to 44%).